This interface is a debugging interface that allows application developers to monitor (spy on) memory allocation, detect memory leaks, and simulate memory failure in calls to IMalloc methods.

**Caution   **The IMallocSpy interface is intended only for use in debugging application code under development. Do not ship this interface to retail customers of your application because it causes severe performance degradation and could conflict with user-installed software to produce unpredictable results.

When to Implement

Implement this interface to debug memory allocation during application development.

When to Use

When an implementation of IMallocSpy is registered with the CoRegisterMallocSpy function, COM calls the pair of IMallocSpy methods around the corresponding IMalloc method. You would not make direct calls to IMallocSpy methods. The call to the pre-method through the return from the corresponding post-method is guaranteed to be thread-safe in multithreaded operations.


The following table shows the methods for this interface in the order that the compiler calls the methods. Like all COM interfaces, this interface inherits the methods for the IUnknown interface.

IUnknown method Description
QueryInterface Returns pointers to supported interfaces.
AddRef Increments reference count.
Release Decrements reference count.
IMallocSpy method Description
PreAlloc Called before invoking IMalloc::Alloc, and may extend or modify the allocation to store debug information.
PostAlloc Called after invoking IMalloc::Alloc.
PreFree Called before invoking IMalloc::Free.
PostFree Called after invoking IMalloc::Free.
PreRealloc Called before invoking IMalloc::Realloc.
PostRealloc Called after invoking IMalloc::Realloc.
PreGetSize Called before invoking IMalloc::GetSize.
PostGetSize Called after invoking IMalloc::GetSize.
PreDidAlloc Called before invoking IMalloc::DidAlloc.
PostDidAlloc Called after invoking IMalloc::DidAlloc.
PreHeapMinimize Called before invoking IMalloc::HeapMinimize.
PostHeapMinimize Called after invoking IMalloc::HeapMinimize.


To determine whether the platform supports this interface, see Determining Supported COM APIs.


OS Versions: Windows CE 3.0 and later.
Header: Objidl.h, Objidl.idl.
Link Library: Ole32.lib

See Also

CoGetMalloc | CoRegisterMallocSpy | IMalloc | IMalloc::Alloc | IMalloc::DidAlloc | IMalloc::Free | IMalloc::GetSize | IMalloc::HeapMinimize

Last updated on Wednesday, April 13, 2005

© 2005 Microsoft Corporation. All rights reserved.